JAXA’s Venus Climate Orbiter
(PLANET-C) overview
Launch: Jun 2010
Arrival: Dec 2010
Mission life: 2 years
Venus and Earth
• They have almost the same size and mass.
• Surface environments are completely different.
(Venus’ environment: CO2 atmosphere, no ocean,
92bar, 740K, H2SO4 cloud ..)
• What differentiated these planets? How does the
climate system work under different conditions?
Science goals
• Atmospheric dynamics
– Mechanism of super-rotation
– Meridional circulation
– Meso-scale processes
– Lightning
– Cloud physics
• Detection of active volcanism
• Inhomogeneity of surface material
• Zodiacal light
Hierarchy of Earth’s meteorology
ÅMacroÆ ÅMesoÆ ÅMicroÆ
1sec
10min
1hr
6hr
2d
20d
1yr
10yr
Planetary
Climate
wave
change
Baroclinic instability
Tropical cyclones
Cloud cruster
Inertio gravity wave
Cumulus convection
Gravity wave
Boundary layer
Wave breaking
Boundary layer
turbulence
Interaction
104 km
103 km
102 km
10 km
1 km
100 m
10 m
Hierarchy of Venus’ meteorology
ÅMacroÆ ÅMesoÆ ÅMicroÆ
1sec
10min
1hr
6hr
2d
20d
1yr
10yr
Super-rotation 104 km
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?
?
?
?
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?
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103 km
102 km
10 km
Upscale cascade
to super-rotation?
1 km
100 m
10 m
Forbes (2002)
Concept of meteorological satellite
• Monitoring global structure
o
Æ Wide field of view (12 )
• Covering wide-range of time scales
Æ Continuous, systematic sampling
(every 2 hours)
• Local time coverage
Æ Equatorial orbit
• Meso-scales / Wind vectors
Æ High spatial resolution (~10 km)
Spacecraft
Mass 480 kg
(including fuel)
Science payload 34 kg
Attitude control
o
Pointing accuracy 0.1
Stability 0.01o
Oribit
Periapsis 300km
Apoapsis 13 Rv
Period 30 hours
12o FOV
Science instruments (1)
1-μm camera (IR1) by Tokyo U.
λ= 1.01 μm (near-IR window)
Pixels: 1024x1024, Detector: Si-CSD/CCD
Æ Cloud (day/night)
Æ Active volcanism / surface emissivity (night)
2-μm camera (IR2) by Kumamoto U.
λ= 1.73, 2.26, 2.32 μm (near-IR window),
2.02 μm (CO2 absorption), 1.65 μm (zodiacal light)
Pixels: 1024x1024, Detector: PtSi
Æ Cloud / Particle size
Æ Carbon monooxide (night)
Æ Cloud top height (day)
Galileo (2.3μm)
Æ Zodiacal light (cruising)
Science instruments (2)
UV imager (UVI) by Hokkaido U.
λ= 283, 365 nm
Pixels: 1024x1024, Detector: SiCCD
Æ SO2 / Unknown UV absorber (day)
Longwave IR camera (LIR) by Inst. of Polar Res.
λ= 8-12 μm
Pixels: 240x320, Detector: uncooled bolometer
Æ Cloud top temperature (day/night)
Lightning and Airglow camera (LAC) by Tohoku U.
λ= 777, 551, 553, 558, 630 nm
Pixels: 8x8, Detector: APD (50kHz sampling)
Æ Lightning (night)
Æ O2 /O airglow (night)
Science instruments (3)
Sensor Digital Electronics unit (DE) by JAXA
Controlling observation sequence of cameras
Onboard calibration
JPEG2000 data compression
Ultra-stable oscillator (Radio science) by JAXA
~10-13, provided by Timetech Co.
Æ Temperature profiles
Æ H2SO4 vapor profile
Æ Ionosphere
To the earth
Atmosphere
Usuda deep
space center
Spacecraft
motion
X-band beacon
1-μm camera
Lightning and airglow camera
2-μm camera
Longwave IR camera
Ultraviolet imager
Altitude coverage
Unknown
momentum
transport
80
Airglow (Visible)
Radio occultation
Lightning
Cloud top temperature (IR)
Surface (Near-IR)
100
velocity (m s-1)
CO (Near-IR)
Lower cloud (Near-IR)
CO2 absorption (Near-IR)
SO2 /Unknown absorber (UV)
Cloud
layer
60
50
0
0
Sounding region
(km)
100
40
20
Observation sequence in each revolution
300km x 13 RVenus
Period: 30 hours
Inclination: 172 deg
Temperature/H2SO4
vapor by radio
occultation
Limb images
(~1 hour)
Resolution: 0.2-1 km
Resolution: 10-20 km
Global images of
atmosphere and ground
surface (~24 hours)
Close-up images /
Lightning / Airglow
(~3 hours x 2)
Resolution: 1-10 km
Orbital motion roughly synchronized with the
super-rotational flow near the cloud base
Spacecraft
60 m/s westward flow
near the cloud base
Accurate derivation of eddy motions
embedded in the background super-rotation
Derivation of cloud motion
vectors every 2 hours
100-300 km
Movement
with time
Cloud tracked winds on the Earth
3-D global meteorological data
Dayside
Nightside
Temperature
H2SO4 vapor （RS）
Airglow
（LAC）
100 km
SO2 / Unknown
absorber (UVI）
Cloud top
height
（IR2）
Lower clouds
（IR1）
65 km
50 km
35-50 km
Cloud motion
vectors
0 km
Cloud top
temperature
（LIR）
Lower clouds
（IR1/IR2）
Carbon monooxide
（IR2）
Lightning （LAC）
Active volcanism / Surface material （IR1）
Optical sounding of ground surface
• Search for hot lava by taking global pictures
at 1.01μm several times per orbit
• Emissivity distribution of the ground surface
• Cloud feature is distinguished from surface
feature by taking motion pictures and using
1.7μm and 2.3μm images which reflect cloud
feature but not the surface feature.
Schedule
2004
2006
2009
2010
Proto Model (Phase-B) start
Flight Model design/manufacturing start
Final integration test
Launch / Arrival at Venus
IR2 test model
M-V rocket of JAXA